spec: 1017 reasoning-effort A/B — 75 buys nothing over 100 on the new model (86 vs 87, same 1.4s turn); depth sweep closed

specs/tech-architecture/dsv41-1017-tuning.md

@@ -128,14 +128,25 @@ long-context multi-session serving becomes the goal, the lever is
 `--chunked-prefill-size` (with `SPARK_ENGRAM_MAX_IDS` raised accordingly) or
 an admission cap, not more KV.
 
+## Reasoning-effort A/B (2026-10-18 evening)
+
+`SGLANG_DSV41_REASONING_EFFORT` 100 (Aiden's default, our lane) vs 75 (knapcio's
+default), same EP2/2048/1M config, same harness:
+
+| effort | score | Hard Mode | responsiveness | median turn | tg c1 (d0) |
+|---|---|---|---|---|---|
+| 100 | **87/100** | 42/56 (75%) | 75 | 1.4 s | 45.6 |
+| 75 | 86/100 | 41/56 (73%) | 75 | 1.4 s | 40.3 |
+
+**The effort lever does not pay on 1017.** The "max costs 3.5x the reasoning
+tokens" observation belongs to the *old* V4.1-Flash; 1017 at `max` already spends
+~40% of that (stu.miller, forum 382725 #266), so dropping to 75 buys no
+measurable turn time here and costs a point. Lane stays at 100.
+
 ## Not yet measured
 
-- The depth sweep above is now measured (see the table); the concurrent
-  deep-context failure mode is documented rather than fixed.
 - DSPARK `--speculative-dspark-block-size` sweep (3/5/7); accept length on the
   live lane sits at 3.0-5.2 with block 5.
-- `--depth` sweep (16K..256K) on the final config; the 1M context cap is adopted
-  but the long-context rows are unmeasured on this venue.
 - The 2x alternative: thread 386121 / `x00byte/DeepSeek-V4.1-Flash-1017-Dual-Spark`
   (TensorFold + vLLM on EXL3 2.9bpw, decode c1 59-103 tok/s on two Sparks) is a
   different checkpoint + engine; a dgx1+dgx2 (`2nodes-dac`) lane is the natural